Compositions for conventional hot-melt adhesive (HMA) formulations typically follow a general rule of thumb of containing ⅓ polymer, ⅓ tackifier and ⅓ wax. Due to the short supply and increasing cost of tackifier, market demand is growing for HMA formulations containing greater polymer content and less tackifier. However, reducing the amount of tackifier and increasing the amount of polymer has the drawback of deteriorated adhesion and increasing the set time of the HMA composition when using traditional polymers such as ethylene vinyl acetate (EVA) and ethylene-based copolymers. An HMA formulation using propylene/ethylene copolymer having a high melt flow rate can be formulated into an HMA formulation with a higher polymer content and sufficient adhesion performance, but due to propylene-based copolymer's inherently slow crystallization time, set time of the HMA formulation is slower than compositions containing ethylene-based copolymers. A need exists for a HMA composition with reduced tackifier, while maintaining suitable adhesion properties and a rapid set time compatible with high-speed line processing applications.
A need further exists for a HMA composition with a propylene-based polymer having improved high temperature resistance, improved adhesion properties, improved substrate compatibility, and/or improved thermal stability.